Question

I have a bash script that processes some data using inotify-tools to know when certain events took place on the filesystem. It works fine if run in the bash console, but when I try to run it as a daemon it fails. I think the reason is the fact that all the output from the inotifywait command call goes to a file, thus, the part after | while doesn’t get called anymore. How can I fix that? Here is my script.

#!/bin/bash

inotifywait -d -r \
-o /dev/null \
-e close_write \
--exclude "^[\.+]|cgi-bin|recycle_bin" \
--format "%w:%&e:%f" \
$1|
while IFS=':' read directory event file
do

    #doing my thing

done

So, -d tells inotifywait to run as daemon, -r to do it recursively and -o is the file in which to save the output. In my case the file is /dev/null because I don’t really need the output except for processing the part after the command (| while...)

Answer 1

You don’t want to run inotify-wait as a daemon in this case, because you want to continue process output from the command. You want to replace the -d command line option with -m, which tells inotifywait to keep monitoring the files and continue printing to stdout:

   -m, --monitor
          Instead  of exiting after receiving a single event, execute
          indefinitely.  The default behaviour is to exit  after  the
          first event occurs.

If you want things running in the background, you’ll need to background the entire script.